Amorphization of cubic zirconia by caesium-ion implantation

Stabilized cubic zirconia is a promising candidate material for use as an i nert fuel matrix for 'burning' excess Pu in light-water nuclear reactors. Z irconia is also considered to be an excellent nuclear waste form for direct geological disposal. Both applications are based on zirconia's high solubi lity for actinides, high chemical durability and high stability under irrad iation. We report the first evidence of solid-state amorphization of yttria -stabilized cubic zirconia (YSZ) by 400 keV Cs-ion implantation to 1 x 10(2 1) ions m(-2) at room temperature. Amorphization of YSZ is caused by the la rge size incompatibility and low mobility of Ca ions in the YSZ structure, reflecting a relatively low solubility of Cs in YSZ. Nevertheless, the Cs c oncentration at which amorphization of YSZ occurred (about 8 at.%) is well above the value that will typically be reached in an inert fuel matrix.